Feeding calves: It takes more than just milk

Editor's note: The following article originally appeared in the October issue of the Miner Institute Farm Report, available here.

When thinking of calves and what it takes to grow them properly the main component of their diet is milk or milk replacer. However, it’s important to think about the other components of their diets as well. Milk is fed to calves for only a limited time, and the transition to a solid diet is relatively quick. To create a smoother weaning period and maintain growth post-weaning it’s important to encourage intake of more than just milk, even in the pre-weaning period.

The main question is besides milk, what should we be feeding calves to make them grow and transition the best? A concentrate is common throughout most calf programs, but is that all that’s needed? Should some sort of forage be offered? And if so, what kind of forage? There are a number of different views and opinions about this topic, but I’m hoping to shed some light on the advantages of offering forages to calves.

In general and across several different recent studies, in the preweaning period intake of pelleted starter feed does not differ between calves offered forage and those not offered forage. During this period, calves offered forages tend to prefer the forage to the concentrate. In instances where a forage and concentrate were offered as a mixed feed, calves learned sorting behavior at an early age and would sort the offered feed, consuming the forage in higher than expected amounts. Calves that learned this sorting behavior were more apt to continue to sort their rations after weaning compared to those calves offered concentrate and forage as separate components in different buckets.

Post weaning, the preference of the calves shifts to the concentrate over the forage. Perhaps this shift is to make up for nutrients that were previously provided by the milk. During the post weaning period calves with ad libitum access to both forages and concentrates have greater concentrate intake and total dry matter intake, resulting in higher average daily gains compared to calves strictly offered a concentrate.

This greater intake of concentrates is thought to be facilitated by an increase in rumen pH that occurs when forages are consumed, making a better rumen environment giving calves the ability to consume more grain. Calves offered forages also exhibited lower ruminal concentration of volatile fatty acids (VFA), despite the higher intake of concentrates, which may be due to these calves having a greater ability to absorb produced VFA.

A recent study looked at whether these advantages were truly coming from forages or just added fiber in the diet. Total dry matter intake and rumen pH was higher in forage supplemented calves than those offered a high (or low) NDF calf starter. Although simply buying a concentrate with a higher fiber level may be easier, it appears to be more beneficial to provide forage in the calf diet as the same benefits aren’t seen through raising the fiber content of a concentrate.

The type of forage offered to calves can have different effects. In general feeding legume forages results in higher intakes of the forage itself, but doesn’t result in greater intakes of concentrate or total dry matter intake. Calves offered legume forages tend to have a higher weight of the GI tract as a percent of body weight than calves offered just starter grain, or starter grain and grass hay. This indicates that feeding legumes may appear to be beneficial when evaluating weight and gains, but are actually just adding to gut fill and not carcass weight.

Grass hays and silages have been shown to produce greater average daily gains and total dry matter intake. Castells et al. (2012a) studied the effects of six different forage sources; average daily gain of calves offered oat hay, triticale silage, and barley straw were found to be 21-28% greater than calves fed only concentrates.

Any farm that raises its own replacement animals is essentially raising the future of their farm, since calf performance and growth is vitally important. Achieving greater growth and gains of calves should be a high priority on any dairy farm and can be achieved with the correct supplementation of a forage and a concentrate. Providing a good quality grass hay/silage in an ad libitum manner, separate from but in conjunction with a concentrate starting in the first weeks of life and continuing through the post weaning period, will maximize calf performance and growth.